12-07 Exercise 2: Function num_digits

Question

Write a function num_digits(n) that returns the number of digits in n ( a positive integer). Hint: to determine the number of digits in a number n, divide it by 10 repeatedly. when n reaches 0, the number of divisions indicates how many digits n originally had.

寫一個num_digits(n)函數 計算n有幾位數

#include <stdio.h>
int num_digits(int n)
{
   /*INSERT YOUR CODE HERE*/

   /*在這裡寫你的程式*/
   /*END OF YOUR CODE*/
}

int main(void)
{
   int n;
   scanf("%d", &n);
   printf("%d has %d digit(s)",n,num_digits(n));
   return 0;
}

Please complete this program by only insert your code between those tags:

   /*INSERT YOUR CODE HERE*/ 
   /*END OF YOUR CODE*/

Example input

12347

Example output

12347 has 5 digit(s)

Remember: You may correct the cases, but your code always be revised!

Answer 1

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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    *  * ** *** * *  *  ** 
****** *    ***  *** * **  ******  count;
}

int main(void)
{
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***   **    * **** *  ** *  * ****  * *  has %d * * * *  ***     * * * *
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}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 2

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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}

int main(void)
{
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*** **  * *   *** * * ***     0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 3

Hidden content!
#include    **  ** **   **
#include      *** ***  ** 
int num_digits(int n)
{
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}



int main(void)
{
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**    **** *   *  * * *   *  *      ***** &n);
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}

Comments

prog.c: In function 'num_digits':
prog.c:8:6: warning: implicit declaration of function 'abs' [-Wimplicit-function-declaration]
    n=abs(n);
      ^~~

Answer 4

Hidden content!
#include   **  * ** *
#include ****    **** 
int is_prime(int n)
{
** *** *  ** ** * * *  divisor;
if (n<=1)
  **   ******   *  false;
for (divisor *   *  ** * *   ** *****  
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return true;
}
int main(void)
{
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*  * **  * *** ** * *    **  0;
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 5

Hidden content!
#include  *********    * 
int num_digits(int n)
{
*   *   ** ** ***  *    * 
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}

int main(void)
{
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*    **** ** *  **  **    * ****     has %d * * ***** *****    *    *
* * * ***    ***  * ** 0;
}

Comments

prog.c: In function 'num_digits':
prog.c:7:6: warning: implicit declaration of function 'abs' [-Wimplicit-function-declaration]
    n=abs(n);
      ^~~
prog.c:8:16: warning: implicit declaration of function 'log10' [-Wimplicit-function-declaration]
    return (int)log10(n)+1;
                ^~~~~
prog.c:8:16: warning: incompatible implicit declaration of built-in function 'log10'
prog.c:8:16: note: include '<math.h>' or provide a declaration of 'log10'

Answer 6

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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**  ****  *  ****   ***    * != 0)
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* * *** ****  * *  * ** 
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}

int main(void)
{
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***  ***** * ****  ***     * * **  *    **  **  &n);
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}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
            *  **     cnt=0;
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int main(void)
{
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*  **   **  * *     ***** * * ***     * * has %d  ***    * **  *** *** *
 *   ***   ***** *  *** *  * *  0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 8

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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*** * **    **** * *    * *
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}
int main(void)
{
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**   ***   *  * * * * **   *   **  * **  ** * * &n);
*****  * *  * ***  *     ** ** * **   * *  * has %d * **  *  * *** *  * *** * *
** ***** ** * *   * ****** 0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 9

Hidden content!
int num_digits(int n)
{
  **  *  *   **** **    num_digit=0;/*INSERT YOUR CODE HERE*/
**  * ** ***** * **    *** ***
 * ** *   *  ***   ***  
*  *   *  * ** **  * **  **    * **  ** **       ** 
*   * *  *  * ** ** *   *   **  * * **  * ***
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***   *  ** * **** * *  * *  *   ** * * **
   **** **** * ***    *** * *  OF YOUR CODE*/
**  *   **   *  ***** num_digit;
}

int main(void)
{
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*   *     *   *  *  *** *** ** *   has %d  ****  ** * * **** ***  *
   *** ** ** ** *  *** *   0;
}

Comments

prog.c: In function 'main':
prog.c:18:4: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    scanf("%d", &n);
    ^~~~~
prog.c:18:4: warning: incompatible implicit declaration of built-in function 'scanf'
prog.c:18:4: note: include '<stdio.h>' or provide a declaration of 'scanf'
prog.c:19:4: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    printf("%d has %d digit(s)",n,num_digits(n));
    ^~~~~~
prog.c:19:4: warning: incompatible implicit declaration of built-in function 'printf'
prog.c:19:4: note: include '<stdio.h>' or provide a declaration of 'printf'

Answer 10

Hidden content!
int num_digits(int n)
{
** ** **  **    *  count=0;/*INSERT YOUR CODE HERE*/
* *******   **      * * 
    ***   *****    *  *
     *   * * ** * **    * * *** * ****  *  ***    ** *
*  ****   *** ****** * **** ****  *    ***** **  
   * ** * *  **  *   **

* ** ** ***   **  * ***** * **  ***  **
**** **  ** * **   *** OF YOUR CODE*/
*  *** ** * **  **  * count;
}

int main(void)
{
*  * **  *** *** ** ** n;
*****  *    * * * **** ** **  *  * ** *   *  &n);
* * * ** ** * *  **  * * **   has %d **   * * * *** * ***** 
***   *      **      0;
}

Comments

prog.c: In function 'main':
prog.c:18:4: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    scanf("%d", &n);
    ^~~~~
prog.c:18:4: warning: incompatible implicit declaration of built-in function 'scanf'
prog.c:18:4: note: include '<stdio.h>' or provide a declaration of 'scanf'
prog.c:19:4: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    printf("%d has %d digit(s)",n,num_digits(n));
    ^~~~~~
prog.c:19:4: warning: incompatible implicit declaration of built-in function 'printf'
prog.c:19:4: note: include '<stdio.h>' or provide a declaration of 'printf'